I'm not trying to tell you how to build up your bike, but remeber- if you'll only use the platform side 2% of the time, it might be worth it to just use 324's or other commonly available pedals even if they are not your "dream pedals". I know shimano pedals are pretty bullet proof but if you pay a lot of extra money to have a pair of pedals imported from 'across the pond' and something goes wrong with them, there is a chance that your LBS may have trouble getting replacement parts to fix them. Some SPD parts are generic but some are pedal specific and it would stink to ruin a whole tour because you got stuck for 3 days in Burn Corn Alabama waiting on Shimano to send replacement parts for your fancy pedals to "Billy-Bobs Bikes, Live Bait, and Used Car Autorama".
I know life is full of "What If's" and you can't plan for all of them but importing pedals to achieve a negligable comfort difference for 2% of your riding seems like buying an airplane to get free peanuts. Yeah, it'll work but there are better ways to do it.